Device for data transmission between vehicle sensors and a processor in a controller

ABSTRACT

A device is proposed for data transmission between vehicle sensors and a control unit, which is used to decode data telegrams having sensor data from the vehicle sensors and to reformat them into SPI (serial peripheral interface) data telegrams. Furthermore, an interface module of the control unit will then transmit the SPI data telegrams to the processor of the control unit. By using an alter bit, it is possible for the processor of the control unit to retrieve either the newest sensor data or the preceding sensor data. The interface module converts the sensor data in each case into a  10 -bit data field of an SPI data telegram, the interface module supplementing missing data if necessary. By counting out the edges, it is possible for the interface module to recognize the data telegrams from the sensors.

BACKGROUND INFORMATION

[0001] The present invention relates to a device for transmitting databetween vehicle sensors and a processor of a control unit, according tothe species defined in the main claim.

[0002] It is known that one may use special data telegrams fortransmitting data between a sensor and a processor in a control unit.

SUMMARY OF THE INVENTION

[0003] As compared to this, the device according to the presentinvention for transmitting data between vehicle sensors and a processorfor the control unit, having the features of the independent claim, hasthe advantage that an interface module is present which may receivefirst data telegrams from a plurality of vehicle sensors and capturesthe data from the first data telegrams, unformatted, and sends them onsynchronously in second data telegrams to the processor within thecontrol unit. It is thereby possible to let various sensorssimultaneously transmit data to the control unit, different formats forthe individual data telegrams between the interface module and thesensors being usable. Therefore, the device according to the presentinvention is extremely flexible and expandable.

[0004] Measures and further developments described in the dependentclaims make possible advantageous improvements in the device describedin the independent claim for transmitting data between the vehiclesensors and a processor of a control unit.

[0005] It is particularly advantageous that the data field of the seconddata telegram is filled up with zeros, if necessary, if, in therespective data telegram from the sensor, there were fewer data than thedata field can accommodate. Thereby, advantageously, the same datatelegram format may always be used for the processor. This leads to asimplified processing of the data.

[0006] In addition, it is of advantage that a memory of the interfacemodule is present, which is used for the temporary storage of sensordata, so that a processor may retrieve old or new sensor data. This isparticularly advantageous when a sensor fails, and thus the precedingsensor data are still available for further processing. This case maycome up particularly when there is a collision, in which vehicle sensorsthat are situated peripherally in the vehicle are damaged by the impact.

[0007] Finally it is also of advantage that the interface modulereceives the data telegrams from the vehicle sensors in 13-bit dataframes, and, in so doing, counts out the edges of the data frames inorder to recognize the data telegrams. The vehicle sensors areadvantageously supplied with electrical energy by the interface module,the data transmission, then, being used for this by a current modulationof the direct current used for the energy supply. The current modulationis less sensitive with regard to EMV problems. Furthermore, Manchestercoding is used, so that only two different current levels are used.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Exemplary embodiments of the present invention are represented inthe drawings and are explained in detail in the following description.The figures show:

[0009]FIG. 1 a block diagram of the device according to the presentinvention,

[0010]FIG. 2 a flow chart of a method according to the presentinvention,

[0011]FIG. 3 a data telegram frame of a sensor,

[0012]FIG. 4 the assignment of the data to an SPI data field,

[0013]FIG. 5 an SPI data frame, and FIG. 6 an SPI line.

SPECIFICATION

[0014] Because of the increasing integration of ever more sensors into amotor vehicle, which are used for sensing a vehicle crash, it isnecessary to open up the possibility, even for future sensors havingchanged data telegrams, of transmitting data to the processor of acontrol unit that is already present. For this, an interface module isprovided, according to the present invention, which receives theindividual data telegrams from the vehicle sensors and reformats thedata into SPI (serial peripheral interface) data telegrams, in orderthen to transmit them in such SPI data telegrams to the processor. Inthis context, advantageously, the interface module is connected to amemory which temporarily stores sensor data, and an alter bit makes itpossible for the processor to select whether the current sensor data areto be transmitted to it or the preceding sensor data. Thus, the SPI datatelegrams are not only transmitted by the interface module to theprocessor, but also the other way around.

[0015] SPI (serial peripheral interface) transmission is datatransmission between a master, a processor and several slaves, which arethe individual components in a control device such as the interfacemodule according to the present invention, or a firing circuit controlwhich is used for monitoring and firing the igniters for means ofrestraint. The SPI transmission is a bidirectional and synchronoustransmission. FIG. 6 shows an SPI line which itself has five individuallines. Since we are talking about synchronous transmission, a timingcircuit denoted as Clk is present. For data transmission from the masterto a slave there is a MOSI (master out, slave in) line, but for datatransmission from a slave to the master, a MISO (master in, slave out)line is present. In order to select the appropriate slave, the CS (chipselect) line is used. In order to release the SPI data transmission, anenable line, here denoted as EN, is used. The SPI line starts at themaster and then branches out to the individual slaves, the SPI line,however, always having the five single lines.

[0016]FIG. 1 shows a block diagram of the device according to thepresent invention. A sensor 1, such as an acceleration sensor, asperipheral sensor is connected to a first data input of an interfacemodule 3 via a data input. A sensor 2, here a pressure sensor, isconnected to interface module 3 via a second input of interface module3. Interface module 3 has a memory unit 4. Interface module 3 isconnected to a processor 5 via a first data input/output. For this anSPI line 6 is installed. SPI line 6 branches from processor 5 to anignition drive circuit 51 as well. Processor 5, interface module 3, SPIline 6, ignition drive circuit 51 and memory 4 are elements of a controlunit 7. Control unit 7 is in this case uesd for the control ofrestraining systems. However, other application areas are alsoconceivable.

[0017] Interface module 3 has means for data transmission and means forsignal processing, in order to be able to attend to the task ofreformatting. For this purpose, a synchronization, a sequence controland memory 4 are present. Furthermore, interface module 3 has a currentsource for supplying vehicle sensors 1 and 2 with electrical energy.

[0018] The connection to sensors 1 and 2 may also be implemented via abus, additional sensors to sensors 1 and 2 also being able to beconnected to interface module 3. Sensors 1 and 2 transmit their sensordata asynchronously in data telegrams to interface module 3, which takesfrom these data telegrams the useful data and reformats them into SPIdata telegrams, which are then transmitted to processor 5 via SPI line6. Sensors 1 and 2 begin immediately with their asynchronous datatransmission, as soon as they are supplied with energy. In this case,the energy supply takes place via the lines of interface module 3 tosensors 1 and 2. For this, direct current is used here, on which thesensors then modulate their data. Manchester coding is used in thisinstance, in response to which switching back and forth takes placebetween two current levels. Thus, apart from the energy supply, only oneunidirectional data transmission takes place from sensors 1 and 2 tointerface module 3.

[0019] In this connection, interface module 3 conducts a temporarystorage of the received sensor data of a data telegram in memory 4, sothat for processor 5 in each case the current sensor data of a sensorand the preceding sensor data are present in memory 4 in interfacemodule 3. Thus, if a loss of the sensor occurs, processor 5 can accessthe sensor data, which the sensor had produced before it failed.

[0020]FIG. 2 shows the block diagram of the sequence of the deviceaccording to the present invention. In method step 8, sensors 1 and 2send their sensor data asynchronously in first data telegrams tointerface module 3, after they have been supplied with electrical energyvia the line over which the data telegrams are sent. According to that,a powerline data transmission takes place. In method step 9, interfacemodule 3 recognizes the individual data telegrams by counting off theedges of the impulses. In this context, it is possible here to informinterface module 3 by further signals as to which sensors are sendingdata telegrams.

[0021] In method step 10, interface module 3 stores the sensor data inmemory 4, storing each time for each sensor 1 and 2 the current sensorvalue and the preceding sensor value. Method step 14 now checks whetherthe most recent sensor data or the preceding sensor data should betransmitted from memory 4 synchronously via SPI line 6 to processor 5 inSPI frames. This is recognized by whether processor 5 has set an alterbit via an SPI data telegram over the MOSI line or not. If this is thecase, interface module 3 gets the newest data from memory 4 in methodstep 16. If not, then interface module 3 gets the preceding sensor datafrom memory 4 in method step 15.

[0022] In method step 11, reformatting of the data by interface module 3takes place, in that interface module 3 transmits the sensor data to thedata files of SPI frames and, if necessary, fills up the empty spaces inthe SPI data field with zeros. Processor 5 recognizes the zeros as blankinformation. Using the selected sensor data, in method step 12 thetransmission in an SPI data telegram takes place. In method step 13,processing of the sensor data thus transmitted by processor 5 takesplace, for example, whether the restraining systems are to be triggeredor not. Processor 5 here computes the release algorithm for theconnected restraining systems. If the sensor data indicate a crash,then, according to the severity of the crash, which may also be derivedfrom the ensor data, triggering of the restraining systems takes place.

[0023]FIG. 3 illustrates a data frame which is transmitted by sensor 1or sensor 2 to interface module 3. The data frame is made up of 13 bits,and is subdivided in the following manner: first of all, two start bitsare included, marked S1 and S2, which are followed by 10 data bits,which include acceleration data. The data bits are numbered from D0through D9. The deactivation of the data frame is formed by a parity bitfor the plausibility check of the data transmitted in the data telegram.A bit duration of 8 microseconds, for example, is provided here, whereasthe time t_(tran) is specified as 88 microseconds and the total time ofthe data telegram t_(pas) is specified as 28 microseconds. A Manchestercoding is applied, in this context each bit duration being divided upinto two intervals of equal length. In this connection, a logical 1 isrepresented by having the current high in the first half and low in thesecond half. On the other hand, a logical 0 is transmitted by having thecurrent low at first and then high. This scheme guarantees that each bitduration has a transition in the middle, which makes synchronizing easyfor the receiver, that is, interface module 3. A better stability withregard to EMV (electromagnetic compatibility) is achieved by the currentmodulation.

[0024]FIG. 4 represents how the seven data bits of a data telegram of asensor, here of sensor 2, are transmitted to the 10 data bits of the SPIdata field. Since the SPI data field has two bits more than the 8 dataof the sensor data telegram, the first two bits are set using zeros.This is to ensure that the data telegrams of the sensors each havefewer, or at most as many data bits as the SPI data telegrams have. FIG.5 shows such a data telegram of an SPI data frame. It begins with astart bit SI which is followed by a synchronization bit 15, which is setby a 1. Bits 14 and 13 form a channel address, while bit 12 is the alterbit. The alter bit is set here as 0, and it means that the sensor isrequesting the newest sensor value from interface module 3. Bits 11 and10 are additional formatting data, upon which there follow the 10 databits which have the actual sensor data.

What is claimed is:
 1. A device for transmitting data between vehiclesensors and a control unit (7), the data transmission taking placeasynchronously, using a first data telegram from one specific vehiclesensor to the control unit, wherein the control unit (7) has aninterface module (3) which decodes the first data telegram having sensordata from the specific vehicle sensor (1, 2) and reformats it into asecond data telegram; and the interface module (3) synchronouslytransmits the second data telegram to the processor (5) of the controlunit (7).
 2. The device as recited in claim 1, wherein the interfacemodule (3) in each case copies the sensor data into a data field of thesecond data telegram, the interface module (3) supplementing missingdata.
 3. The device as recited in claim 1 or 2, wherein the interfacemodule (3) has a memory (4) for the temporary storage of the sensordata; and the second data telegram has an alter bit for selecting thesensor data of the specific vehicle sensor (1, 2), the memory (4) havinga first data field for old sensor data and a second data field for newsensor data for each vehicle sensor (1, 2), and the processor (5) setsthe alter bit.
 4. The device as recited in one of the preceding claims,wherein the interface module (3) receives the first data telegram fromthe specific vehicle sensor in 13-bit data frames; and the interfacemodule (3) counts out the edges of the data telegrams in order torecognize the data telegrams.
 5. The device as recited in one of thepreceding claims, wherein the interface module (3) supplies the vehiclesensors (1, 2) with electrical energy.
 6. The device as recited in oneof the preceding claims, wherein the specific first vehicle sensor (1,2) creates the first data telegram by a current modulation.
 7. Thedevice as recited in one of the preceding claims, wherein the specificvehicle sensor (1, 2) uses a Manchester coding for the first datatelegram.